As a lithium battery, for example, there are primary and secondary batteries, in which a chalcogen compound is used for a positive active material and metallic lithium is used for an anode. This type of battery has generally been composed of a cathode including a cathode composite, an anode including metallic lithium (forming the negative active material), and a separator. This type of battery has been formed by laying the cathode on the anode through the separator and by housing this laminate in a battery can or filling its peripheral edge with a sealing agent. Particles of positive active material, particles of carbon (such as carbon black) forming a conductive agent, polytetrafluoroethylene or solid polymer electrolyte (serving as a binder) and an organic solvent (serving as a diluent) are mixed and formed into a paste and either filled in or applied onto a substrate such as a stainless steel net or stainless steel plate, thus forming the cathode composite. The anode is formed by sticking a metallic lithium sheet onto the stainless steel plate or composed of the metallic lithium sheet alone.
However, the cathode composite has the following problems. When mixing the above materials to form a paste, the positive active material and the conductive agent cohere so as to worsen the wetting of them with the binder and organic solvent. For this reason, uniform mixing and uniform application on the substrate has been difficult, and additionally a surface of the prepared cathode composite is not uniform forming a corrugated shape. Therefore, the positive active material, the conductive agent and the binder are not dispersed uniformly in the above-mentioned cathode composite, so that the cathode composite sometimes cracks or peels off from the substrate. In addition, the initial capacity has been small as compared with the theoretical capacity in the primary battery using the above cathode composite, and the capacity is lowered to a value smaller than a half the initial capacity at 100 cycles in the secondary battery. Further, in the battery using the above cathode composite, convex surface portions have sometimes broken through the separator to reach the anode causing a short- circuiting.
This invention is made in order to solve the foregoing problems. An object of this invention is to provide a cathode composite, in which cracking, peeling-off from a substrate and short-circuiting can be prevented. Additionally with the invention a good discharge characteristic can be exercised when used in either a primary or secondary battery.